No, this docking station works with any device that uses a Lightning charger, although it is not made for iPad use, so I would only use it with smaller Lightning-compatible devices, such as iPhone 5 and newer, iPod (latest generations), etc.

On the bottom there is a rubber foot and it's weighted for stability. It's wider because of the iPhone 6Plus. It does move side to side on the connector. Also you do need to hold down the dock to remove your phone from the charger. So it is not that heavy but its stable enough to hold the iPhone 6 and 6Plus

The 6 and 6s are very similar. The 6s is slightly thicker, but so unnoticeable that most cases that fit the 6 will fit the 6s. I personally like the dock for my 6s, as it allows an upright position for my phone without being too bulky. But I must admit that it doesn't do anything beyond what it promises--it's just a charging dock. If you just want your phone charged, spending $50 on a dock when your phone comes with a cord is a bit unnecessary, but if you care about aesthetics and having your phone charging upright, then go with the dock.

I bought an iPhone 6S and tech21 case recommended by Apple from the Apple store and the Lightning dock does not work with the case as it can't enter al the way into the charging port. So have to take the case off to use this - so will not be using unfortunately.

I've used my 7th gen nano with an old 30 pin dock and lightening adapter to connect to the analogue input of a JBL Flip, and I'm sure this gives superior sound quality compared to the bluetooth connection.